Analysis of blurring due to short T₂ decay at different resolutions in ²³Na MRI

The nuclear magnetic resonance signal from sodium (²³Na) nuclei demonstrates a fast bi-exponential T₂ decay in biological tissues (T_2,short = 0.5-5 ms and T_2,long = 10-30 ms). Hence, blurring observed in sodium images acquired with center-out sequences is generally assumed to be dominated by signal attenuation at higher k-space frequencies. Most of the studies in the field primarily focus on the impact of readout duration on blurring but neglect the impact of resolution. In this paper, we examine the blurring effect of short T₂ on images at different resolutions. A series of simulations, as well as phantom and in vivo scans were performed at varying resolutions and readout durations in order to evaluate progressive changes in image quality. We demonstrate that, given a fixed readout duration, T₂ decay produces distinct blurring effects at different resolutions. Therefore, in addition to voxel size-dependent partial volume effects, the choice of resolution adds additional T₂-dependent blurring.